Brake Flud Flush
06-13-2001, 12:06 PM
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Brake Flud Flush
I'm still getting adjusted to the new format, so this is double posted on the 944 & S2 forum.
I own an '86 944 na and it is come to my attention that the brake fluid needs to be flushed occasionally (It has been AT LEAST 7-10 years since this was done). I need to replace the brake line between the resovoir and the firewall (covered with blue cloth). Following the recommendation of a rennlister I am planning to use fuel line for this job. I figured that this would be the perfect opportunity to flush the system. I am familiar with the bleeding process, but not the flushing procedure. I was hoping somebody could help.
Thanks,
Jeff
I own an '86 944 na and it is come to my attention that the brake fluid needs to be flushed occasionally (It has been AT LEAST 7-10 years since this was done). I need to replace the brake line between the resovoir and the firewall (covered with blue cloth). Following the recommendation of a rennlister I am planning to use fuel line for this job. I figured that this would be the perfect opportunity to flush the system. I am familiar with the bleeding process, but not the flushing procedure. I was hoping somebody could help.
Thanks,
Jeff
06-13-2001, 01:16 PM
#2
Nordschleife Master
Better make sure that fuel line can take brake fluid exposure.
7 to 10 years is way too long for not changing out brake fluid - the fluid is hydroscopic and picks up moisture from the atmosphere. The big problem with that, besides reducing boiling point and therefore brake performance, is that the water starts to rust your internal brake system. Anyway, what is done is done, but that is why your fluid is dark brown (rust particles) and don't be surprised if seals fail or you spring a leak in the future.
The easiest way to flush which will do a good enough job is to proceed like bleeding, which you say you know how to do, except you keep bleeding until the fluid coming out runs clear. Use a piece of white paper as a background color gauge to tell how clear you are getting, and I would rather flush extra to be sure. Don't let any air into the system like what would happen if you just opened up the bleeder screws and let it drain out. Flush the clutch system also (if you have one) as it has the same rust issue.
Finally, get a positive pressure bleeder (not vacuum) for about $40 from someone like Paragon Products. It will make the job sooooo much easier, especially the clutch. Just ask ANYONE that has done this job on a 944 before. ANYONE.
7 to 10 years is way too long for not changing out brake fluid - the fluid is hydroscopic and picks up moisture from the atmosphere. The big problem with that, besides reducing boiling point and therefore brake performance, is that the water starts to rust your internal brake system. Anyway, what is done is done, but that is why your fluid is dark brown (rust particles) and don't be surprised if seals fail or you spring a leak in the future.
The easiest way to flush which will do a good enough job is to proceed like bleeding, which you say you know how to do, except you keep bleeding until the fluid coming out runs clear. Use a piece of white paper as a background color gauge to tell how clear you are getting, and I would rather flush extra to be sure. Don't let any air into the system like what would happen if you just opened up the bleeder screws and let it drain out. Flush the clutch system also (if you have one) as it has the same rust issue.
Finally, get a positive pressure bleeder (not vacuum) for about $40 from someone like Paragon Products. It will make the job sooooo much easier, especially the clutch. Just ask ANYONE that has done this job on a 944 before. ANYONE.
06-13-2001, 01:22 PM
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Dan,
Thanks for the help! The job dosen't sound like it will be too difficult, I had planned on buying the pressure bleeder you suggested.
I have never bled the clutch system. What is the procedure for that??
Jeff
Thanks for the help! The job dosen't sound like it will be too difficult, I had planned on buying the pressure bleeder you suggested.
I have never bled the clutch system. What is the procedure for that??
Jeff
06-13-2001, 02:19 PM
#4
Nordschleife Master
Clutch is basically the same as brakes, except it is pretty tight under there to get at the bleeder nipple on the slave cylinder and it is MUCH harder to clear if you get air into the system.
You bleed from the the nipple at the back of the slave, which is underneath on the bellhousing. Depending on what type of tools you have you will probably have to remove the starter to get a wrench on the nipple.
Do everything in your power not to get air in the clutch system. The design of the slave is poor and will trap air and make it a nightmare to purge, but should go OK with a pressure bleeder.
If you screw up and get air trapped in the slave, there are several tricks to use, all of which are a pain in the ***. They include removing the slave and tilting it and bleeding and reinstalling, jacking the rear end way up high and bleeding (not too safe in my mind), back filling with a big animal syringe being careful to suck out excess from the reservoir, etc. All of which you want to avoid.
Your most likely screw up points are letting air get in from the top, through the nipple by not having a solid fluid air lock, or having air get in from around the threads of the bleeder nipple.
You bleed from the the nipple at the back of the slave, which is underneath on the bellhousing. Depending on what type of tools you have you will probably have to remove the starter to get a wrench on the nipple.
Do everything in your power not to get air in the clutch system. The design of the slave is poor and will trap air and make it a nightmare to purge, but should go OK with a pressure bleeder.
If you screw up and get air trapped in the slave, there are several tricks to use, all of which are a pain in the ***. They include removing the slave and tilting it and bleeding and reinstalling, jacking the rear end way up high and bleeding (not too safe in my mind), back filling with a big animal syringe being careful to suck out excess from the reservoir, etc. All of which you want to avoid.
Your most likely screw up points are letting air get in from the top, through the nipple by not having a solid fluid air lock, or having air get in from around the threads of the bleeder nipple.
06-13-2001, 07:10 PM
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Do yourself a favor and get Speed Bleeders, especially if you are doing the job yourself. You can loosen them to let the fluid out but they will not allow air to get back in. You can get these from most places - I got mine from Paragon
Also, I used ATE Super Blue to change the fluid - it was very easy to tell when the old was out and the new was in. You can alternate between ATE Blue and ATE Gold when doing different flushes. Our local PCA requires that the fluid be changed every 6 months for doing Drivers Ed events.
On a side note, to get all of the old fluid out you need to retract the caliper pistons and let the fluid drain through the bleeder valves. I found this out when I changed the brake pads after I had put in ATE Blue. What came out of the pistons was very black and not nice looking.
Also, I used ATE Super Blue to change the fluid - it was very easy to tell when the old was out and the new was in. You can alternate between ATE Blue and ATE Gold when doing different flushes. Our local PCA requires that the fluid be changed every 6 months for doing Drivers Ed events.
On a side note, to get all of the old fluid out you need to retract the caliper pistons and let the fluid drain through the bleeder valves. I found this out when I changed the brake pads after I had put in ATE Blue. What came out of the pistons was very black and not nice looking.
06-13-2001, 07:46 PM
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AAHHHHHHHHHHHHH... don't use fuel line for that hose, Porsche makes it blue for a reason. Brake fluid will eat cotton braided fuel line is a few weeks. Buy Porsche part number 999-181-021-50, it's 21.95 per meter list, and has a much higher silicon contend than fuel line. that is the correct hose for that application, fuel hose is not recommended.
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06-15-2001, 02:53 AM
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Intependent Volkswagen parts houses use the blue braded brake like as well, check the size precisely but it might save you a few bucks. I have been using the blue braded VW line for years on German vehicles. Again just be sure of the size. It should be sold by the foot.
